The Quality of Jute Mallow Seeds Exposed to Different Hot Water-Steeping and Cooling Protocols

摘要

Steeping of dormant jute mallow ( Corchorus olitorius L.) seed in hot water at high temperature for enhanced germination, seems to be the most favoured of all other methods. Literature however, appears to be silent on the cooling protocol to adopt to ensure high quality after a seed lot may have been steeped in hot water. Seeds of two cultivars of this crop were subjected to nine hot water/cooling treatments and then dried back. They were then thinly spread and stored in open glass dishes at 83% relative humidity and 33°C. The moisture content of seeds steeped in water at 80 and 97°C increased from about 5-6% prior to storage to about 10-11% after 6-18 weeks after storage (WAS). Steeping of seeds at 80 and 97°C for 5 seconds significantly enhanced germination to about 88% and 77% in ‘Amugbadu’ and ‘Oniyaya’ respectively compared to about 8% in the control (unsteeped) seed. Cultivar ‘Amugbadu’ seeds steeped in cold water (ca 27°C) immediately after steeping in water at 97°C recorded higher germination percentage of 90% - 46% within 0-12 weeks of storage compared to the range of 88 to 29% recorded within the same period in seeds that were simply left to gradual cooling in ambient condition. ‘Oniyaya’ seeds exhibited no differential response to cooling protocol. Unsteeped (control) seed of both cultivars recorded higher germination of 82/85% at 20 WAS than seeds steeped at 97°C (irrespective of cooling protocol) and 80°C prior to storage. Furthermore, whereas seeds of the latter group germinated slower and less uniformly as storage progressed, a gradual increase in the values of these vigour indices were recorded in the former group of seeds. Across steeping treatments the germination percentage of ‘Oniyaya’ seed declined less rapidly than that of ‘Amugbadu’ seeds during storage from ca 61% to 32% in the former compared with about 62% to 3% in the latter.